One of the most significant developments in weed science in recent years is herbicide tolerant field corn cultivars. Herbicide tolerant field corn cultivars can offer benefits in the environmental arena. Unlike insect control, where crops can be genetically transformed to be resistant to insects, there is no current technology available that would make corn resistant to weeds. However, a number of field corn cultivars can be genetically transformed such that they are resistant to herbicides that have more environmentally favorable attributes than some of the herbicides currently in use.

One such herbicide is glufosinate-ammonium, a non-selective, postemergence herbicide currently being developed for the management and control of grass and broadleaf weeds in field corn and other crops. Glufosinate-ammonium is the synthetic equivalent to a naturally occurring compound, phosphinothricin, which is a metabolite of the soil bacteria Streptomyces viridochromogenes. A field study conducted on a conventional till site planted to glufosinate resistant corn (DK574GR) evaluated glufosinate-ammonium at two rates and at three different times of application for control of redroot pigweed, common lambsquarters, large crabgrass and common ragweed. A preemergence treatment of Prowl TM and Bladex TM was included as a standard recommendation.

Excellent broadspectrum weed control was obtained with glufosinate-ammonium at all rates and application periods. Use of glufosinate-ammonium alone at three application timings gave equal or greater control of the annual weed spectrum than the standard preemergence herbicide recommendation with no reduction in weed control or corn grain yields as a result of the delayed treatments. Use of these herbicide tolerant crops will open new weed management opportunities, fit better into a variety of cultural practices and offer more efficient weed management, as well as be more environmentally friendly.

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